Different phone models have different battery sizes and charging profiles therefore take different amounts of time to charge, with large batteries especially taking longer. Charging speeds may also slow at ≥80% in IOS models due to Apple software requirements designed to limit battery deterioration during wireless charging.
InvisQi recognizes IOS charging signals and corresponds by adapting charging speeds until your device requests more power. Please try turning OFF ‘Optimized Battery Charging’ in your ‘Settings’.
Charging speeds will also vary depending on the surface thickness. Thicker surfaces will reduce charging efficiency due to the greater distance the charging signal needs to travel.